As incomes rise in China people will demand other things from the government than food, shelter and a comfortable middle class life. Hong Kong was ahead of the rest of China since they have been living pretty liberal under UK rule and were more prosperous. Whatever they do in Hong Kong now will not stop from things happening all over China at a given point.
This was the theory during the Clinton administration and, to be blunt, that theory has been wrong. The Chinese people do not see risking growth disruption as worth what the west considers freedom. The west has fundamentally failed to make that case to them and even now western democracy is on the decline. Please, please do not take a free China for granted. Do not think that change — that democracy and freedom — is…
I wouldn't be so quick to chalk this up to some sort of spontaneous decision originating with the Chinese people.
Remember that any sort of political dissent or organization tends to be quickly and effectively quashed in China by the authorities. Leaders and activists are imprisoned, tortured, disappeared, or "reeducated". The media and education systems are tightly controlled to only show and teach what the authorities want, and as a result the rest of the population (minus the "counterrevolutinary" leaders and activists, who've been weeded out) has been manipulated to think the way the authorities want them to think and say things the authorities want them to say, and if they don't there are very real consequences.
That said, as long as mainland China is prosperous and more and more people are lifted out of poverty, it's unlikely to have a real revolution. HK is in a different position, as they were already prosperous and have faced worsening conditions since they've been under the Chinese yoke.